Police cameras are popular among neighborhood watches and other civic groups as a way to prevent crime. The Common Council has approved 19 new cameras in places afflicted by high crime. All cameras are paid for by state and federal grants.

A preliminary study in 2011 found cameras led to a decrease in crime during their first six months. The nine Near West Side cameras were credited with reducing most types of violent and property crimes, with the exceptions of gunfire and vandalism.

But researchers hired by the department noted that six months was too short a time to easily distinguish the impact of the cameras from normal peaks and valleys in crime. For example, there weren’t enough gunfire complaints to determine if the cameras had any deterrent effect.

Syracuse police have used footage from the Near West Side cameras in investigations ranging from homicides to hit-and-run crashes. The department does not track if the footage helped police identify or catch a criminal.

Officers looked at footage 86 times from March 28, 2011 to Dec. 17, 2012, records show.

The footage was used 29 times for shootings or reports of gunfire and 23 times for drug complaints, according to police records. It was looked at seven times for robberies, five times for stabbings and five times for homicides.

Those figures are based on the number of times the chief’s office has given permission to view footage from a single camera. One crime could include more than one request. For example, officers viewed footage at least twice for one homicide.

• Cameras have helped as evidence in numerous other cases, police said. Those included drug cases, a shooting and an officer-involved shooting. Police declined requests to elaborate on how the cameras helped in these crimes, citing the need to keep techniques confidential.

Syracuse police Chief Frank Fowler said cameras were working as police thought they would. Expanding the cameras will help track down criminals and prevent crime, he said.

“The Syracuse crime cameras continue to be an important tool in our arsenal to combat and prevent crime in our community,” Fowler said. “As our network of crime cameras expands throughout the city, it will help us to identify, apprehend and prosecute criminals. We are eager to get the new cameras up and working.”

In the six months after cameras were installed, police calls dropped by 10 percent from the same period the year before. There were 1,501 reported crimes, down 34 percent from the year before. Nearly every other major type of crime dropped, including a 16 percent drop in gunfire. The number of arrests dropped, too, by 43 percent.

However, the director of the Finn Institute strongly cautioned against comparing data from year to year. He said other factors that reduce crime could be mistakenly attributed to cameras.

“The primary danger is that you’re going to detect some trend in the data that’s not there,” said Robert Worden, also an associate professor of criminal justice at the State University of Albany. “It’s probably going to be a mis-estimate.”

Instead, researchers use statistical formulas that try to pinpoint crimes prevented by the cameras.

The Finn Institute study from fall 2011 also found the Near West Side cameras helped reduce most types of crime, including serious violent crimes, which went down 10.5 percent.

But results varied: drug crimes were reduced by 45 percent while reports of gunfire increased slightly. The report noted that reports of gunfire were so infrequent that it was especially hard to trace the impact cameras had, if any.

Besides noting the limitations of a short time period for study, the report also cautioned that areas not affected by the cameras were included in the data.

Nevertheless, the reductions led researchers “to cautiously conclude that the cameras have indeed had beneficial effects on crime and disorder,” the report stated.

Worden suggested the upcoming study this summer could show the cameras had even a bigger impact than initially thought.

“We advised police that we could not do anything remotely reliable without six months of data,” Worden said. “We promised we would follow up. We’re in the middle of that right now.”

Nationally, very few studies have looked at the long-term effectiveness of police security cameras. Experts do not agree on what impact police security cameras have on crime.